1. Field of the Invention
The present invention relates to an etching method and a bevel etching apparatus.
2. Description of the Related Art
A bevel/backside polymer attached to a bevel portion (chamfered portion of a wafer edge) of a semiconductor wafer (which may be hereinafter just called a “wafer”) contaminates a surface of a device or affects a yield rate of a product.
In response to this, Japanese Laid-Open Patent Application Publication No. 2010-141237 proposes an apparatus that irradiates a bevel portion of a wafer with a laser beam, thereby removing a bevel/backside polymer by etching. The output intensity of the laser beam emitted to the bevel portion is managed by monitoring and controlling a current supplied to a laser generator.
However, even when the current supplied to the laser generator is constant, the output intensity of the laser beam varies due to a malfunction or a temporal change of the laser generator. When an output value of the laser beam is out of order and the failure cannot be detected, the bevel portion of the wafer is liable to be irradiated with the laser beam having power higher than a prescribed value, and is liable to be scraped and chipped.